I have a positive ending Kea story. We deployed 20,000 PS5 APUs (AKA: AsRock BC-250) each is a individual blade computer that was PXE booted.
We started to see strange behavior on the network and it took a bit of trial and error to figure out what was going wrong. Eventually, we traced it down to dnsmasq being unable to keep up with all the DHCP UDP traffic regardless of how we tuned the kernel/networking buffers.
Switched to Kea and all of our problems magically went away.